Eircell Vodafone, the Republic's biggest mobile phone network, signed up fewer new customers in the fourth quarter of 2001 than in just three days during December a year earlier.

Vodafone shares lost almost 4 per cent of their value yesterday on publication of weak average revenue per user figures for the fourth quarter by the world's biggest mobile group.

The firm's shares fell 6.24p sterling to close at £1.54 in London after it said annual average revenue per user fell £7 to £274 in the UK and was down €14 in Germany to €303. Average revenue per user figures are used as a crucial measure of success in the mobile industry, as firms focus on getting added value from customers rather than boosting sales. Eircell has not published such figures since Vodafone acquired it last year. An Eircell spokeswoman said it would publish the figures in June.

Eircell said yesterday it had acquired just 90,000 new subscribers from October to December 31st, 2001, normally the most buoyant sales period for the mobile industry.

Some 72 per cent of Eircell's subscribers are pre-paid customers, a higher figure than most other Vodafone firms in Western Europe. Firms generally want customers to migrate to contracts to increase average revenue per user.

An Eircell spokeswoman said, however, that the firm was happy with overall performance, specifically with figures showing the percentage of revenue generated by data is growing.

Shares in Western Wireless, which owns 80 per cent of Irish mobile operator Meteor, slumped 30 per cent yesterday on fears it would lose lucrative roaming fee revenues in the US after two rivals formed a joint venture to compete with the firm.